xBase1 = [1 0 0];
yBase1 = [0 1 0];
zBase1 = [0 0 1];
F1 = [xBase1;yBase1;zBase1];

xBase2 = [0 1 0];
yBase2 = [-1 0 0];
zBase2 = [0 0 1];
F2 = [xBase2;yBase2;zBase2];

w21 = [1 0 0];

cross(w21, xBase2)
cross(w21, yBase2)
cross(w21, zBase2)